Image recording apparatus

ABSTRACT

An image recording apparatus, including: a drive source foratable forwardly and reversely; a first roller rotatable in a first direction by the forward rotation of the drive source to convey a conveyed medium and rotatable in a second direction reverse to the first direction by the reverse rotation of the drive source; a recording device; a second roller; a first power transmitter which transmits a first-direction driving power to the second roller and not to transmit a second-direction driving power to the second roller, wherein the first-direction driving power is a rotational driving power of the first roller rotating in the first direction, and the second-direction driving power is a rotational driving power of the first roller rotating in the second direction; and a second power transmitter which transmits the second-direction driving power to the second roller and not to transmit the first-direction driving power to the second roller.

CROSS REFERENCE TO RELATED APPLICATION

The present application claims priority from Japanese Patent ApplicationNo. 2012-072601, which was filed on Mar. 27, 2012, the disclosure ofwhich is herein incorporated by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an image recording apparatus configuredto record an image on a sheet.

2. Description of the Related Art

There is conventionally known an image recording apparatus configured torecord an image on a sheet. A conveyance path through which the sheetpasses is formed in the image recording apparatus. Rollers are providedon a plurality of positions on the conveyance path, and these rollersare rotated by a driving power transmitted from a drive source to conveythe sheet through the conveyance path.

To satisfy recent demand for reducing size and cost of the imagerecording apparatus, the number of drive sources provided in the imagerecording apparatus is preferably reduced. That is, the above-describedrollers are preferably rotated by a driving power produced by a commondrive source.

There is known a conveyor mechanism including a plurality of rollersthat are rotated by a driving power transmitted from a common drivemotor. In this conveyor mechanism, a sheet-supply roller, a conveyorroller, and a discharge roller are rotated by the common motor.Specifically, the conveyor roller is rotated forwardly by forwardrotation of the motor and rotated reversely by reverse rotation of themotor. The sheet-supply roller is rotated forwardly by the reverserotation of the motor but is not rotated by the forward rotation of themotor. The discharge roller is rotated forwardly by the forward rotationof the motor but is not rotated by the reverse rotation of the motor.

SUMMARY OF THE INVENTION

Suppose that the above-described conveyor mechanism is mounted in animage recording apparatus having a duplex image recording function, forexample. When images are recorded on both sides of a sheet, thedischarge roller is rotated reversely to convey the sheet in a directionopposite to a normal sheet conveying direction. The sheet conveyed bythe discharge roller in the direction opposite to the normal sheetconveying direction passes through a resupply conveyance path that isformed for duplex image recording and is branched from a main conveyancepath. In the above-described conveyor mechanism, however, the dischargeroller cannot be rotated reversely because the reverse rotation of themotor is not transmitted to the discharge roller. That is, in theabove-described conveyor mechanism, the discharge roller cannot conveythe sheet in the direction opposite to the normal sheet conveyingdirection.

This invention has been developed to provide an image recordingapparatus in which a roller rotatable only in one direction in a certainsituation is made rotatable in a direction reverse to the one directionin another situation.

The present invention provides an image recording apparatus, comprising:a drive source configured to perform forward rotation and reverserotation; a first roller rotatable in a first direction by the forwardrotation of the drive source to convey a conveyed medium in a conveyingdirection, the first roller being rotatable in a second direction by thereverse rotation of the drive source, the second direction being reverseto the first direction; a recording device disposed downstream of thefirst roller in the conveying direction and configured to record animage on the conveyed medium; a second roller disposed downstream of therecording device in the conveying direction; a first power transmitterconfigured to transmit a first-direction driving power to the secondroller and not to transmit a second-direction driving power to thesecond roller, wherein the first-direction driving power is a rotationaldriving power of the first roller rotating in the first direction, andthe second-direction driving power is a rotational driving power of thefirst roller rotating in the second direction; and a second powertransmitter configured to transmit the second-direction driving power ofthe first roller to the second roller and not to transmit thefirst-direction driving power of the first roller to the second roller.

The present invention also provides An image recording apparatus,comprising: a drive source configured to perform forward rotation andreverse rotation; a first roller rotatable in a first direction by theforward rotation of the drive source to convey a sheet in a conveyingdirection, the first roller being rotatable in a second direction by thereverse rotation of the drive source, the second direction being reverseto the first direction; a recording device provided downstream of thefirst roller in the conveying direction to record an image on the sheet,the recording device being reciprocable in main scanning directionsperpendicular to the conveying direction; a second roller provideddownstream of the recording device in the conveying direction; a trayconfigured to hold the sheet; a supply roller configured to supply thesheet on the tray toward the first roller; a first power transmitterconfigured to transmit a first-direction driving power to the secondroller and not to transmit a second-direction driving power to thesecond roller, wherein the first-direction driving power is a rotationaldriving power of the first roller rotating in the first direction, andthe second-direction driving power is a rotational driving power of thefirst roller rotating in the second direction; a second powertransmitter configured to transmit the second-direction driving power ofthe first roller to the second roller and not to transmit thefirst-direction driving power of the first roller to the second roller;a supply power transmitter configured to transmit the second-directiondriving power to the supply roller and not to transmit thefirst-direction driving power to the supply roller; a first roller gearconfigured to receive the rotational driving power of the first roller;a switcher comprising a contact member contactable with a carriage asthe recording device moved in the main scanning directions, the switcherbeing configured to be switched, by contact of the carriage with thecontact member, between a first position at which the switcher iscoupled to the first roller gear and not coupled to the second powertransmitter and coupled to the supply power transmitter and a secondposition at which the switcher is coupled to the first roller gear andcoupled to the second power transmitter and not coupled to the supplypower transmitter; and a controller configured to control the drivesource and the carriage to execute: a first control in which thecontroller controls the drive source to perform the reverse rotation bya first rotational amount in a state in which the switcher is located atthe first position, then controls the drive source to perform theforward rotation by a second rotational amount to convey the sheet to aposition at which an upstream edge of the sheet in the conveyingdirection passes through the first roller, and then controls the drivesource to perform the reverse rotation by a third rotational amount; anda second control in which the controller controls the drive source toperform the reverse rotation by a fourth rotational amount in the statein which the switcher is located at the first position, then controlsthe drive source to perform the forward rotation by a fifth rotationalamount to convey the sheet to the position at which the upstream edge ofthe sheet in the conveying direction passes through the first roller,and then controls the drive source to perform the reverse rotation by asixth rotational amount in a state in which the switcher is located atthe second position.

BRIEF DESCRIPTION OF THE DRAWINGS

The objects, features, advantages, and technical and industrialsignificance of the present invention will be better understood byreading the following detailed description of the embodiments of theinvention, when considered in connection with the accompanying drawings,in which:

FIG. 1 is a perspective view illustrating an MFP 10;

FIG. 2 is an elevational view in vertical cross section schematicallyillustrating an internal structure of a printing section 11;

FIG. 3 is a perspective view illustrating a drive-power transmittingmechanism 50 and conveyor rollers 60, 62, 45;

FIG. 4 is a perspective view illustrating the drive-power transmittingmechanism 50 and the conveyor rollers 60, 62, 45;

FIG. 5 is a plan view illustrating the drive-power transmittingmechanism 50 and the conveyor rollers 60, 62, 45;

FIG. 6 is a schematic view of the drive-power transmitting mechanism 50as seen from a left side, illustrating a power-transmission relationshipamong rollers, belts, gears, and pulleys of the drive-power transmittingmechanism 50;

FIG. 7A is a plan view schematically illustrating meshing states ofgears 51, 75, 78, 88 with a switch gear 51 located at a first powertransmission position, and FIG. 7B is a plan view schematicallyillustrating the meshing states of gears 51, 75, 78, 88 with the switchgear 51 located at a second power transmission position;

FIG. 8 is a table for explaining sheet conveying directions by supplyrollers 25 and conveyor rollers 60, 62, 45, 68, which are determined bya position of the switch gear 51 and a forward or a reverse rotation ofa conveyor motor 71;

FIG. 9 is a block diagram illustrating a configuration of a controller130;

FIG. 10 is a flow chart for explaining a control executed by thecontroller 130 to convey the recording sheet 12; and

FIG. 11 is an elevational view in vertical cross section schematicallyillustrating an internal structure of a printing section 11 that doesnot include third conveyor rollers 45 and a spur 46 in FIG. 2.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Hereinafter, there will be described one embodiment of the presentinvention by reference to the drawings. It is to be understood that thefollowing embodiment is described only by way of example, and theinvention may be otherwise embodied with various modifications withoutdeparting from the scope and spirit of the invention. A multi-functionperipheral (MFP) 10 is used in a state illustrated in FIG. 1. In thepresent embodiment, three arrows illustrated in FIG. 1 indicate up anddown directions 7, front and rear directions 8, and right and leftdirections 9. In the following explanation, the up and down directions 7are defined as up and down directions of the MFP 10 illustrated in FIG.1, i.e., the MFP 10 being in a normal state. Also, the front and reardirections 8 are defined by regarding a side of the MFP 10 on which anopening 13 is formed as a front side, and the right and left directions9 are defined in a state in which the MFP 10 is seen from the frontside. It is noted that the directions illustrated in FIG. 1 are alsoindicated in other drawings in a similar manner. Also, in the followingexplanation, the term “direction” means a one-way direction which isdirected from one point toward another point, and the term “directions”means opposite directions. That is, the term “directions” includes adirection directed from one point toward another point and a directiondirected from said another point toward the one point.

<Overall Structure of MFP 10>

The MFP 10 is one example of an image recording apparatus as oneembodiment according to the present invention. As illustrated in FIG. 1,the MFP 10 includes a printing section 11 at its lower portion. The MFP10 has various functions such as a facsimile function and a printingfunction. The printing function includes a duplex image recordingfunction for recording images on front and back faces of a recordingsheet 12 as one example of a medium to be conveyed (i.e., a conveyedmedium) and a sheet (see FIG. 2). The printing section 11 has theopening 13 in its front face. The MFP 10 includes: a supply tray 20 (seeFIG. 2) on which the recording sheet 12 can be placed; and an outputtray 21 (see FIG. 2). These trays 20, 21 can be inserted or removedthrough the opening 13 in the front and rear directions 8. It is notedthat the MFP 10 can perform image recording not only on the recordingsheet 12 but also on, e.g., a label face of a CD or a DVD. In this case,the CD or DVD is placed on a thin-plate shaped media tray and insertedinto the MFP 10 through, e.g., the opening 13.

As illustrated in FIG. 2, supply rollers 25 are provided on an upperside of the supply tray 20. The supply tray 20 has a sheet-placedportion, i.e., an upper face, on which the recording sheet 12 is placed.The supply rollers 25 can contact the recording sheet 12 placed on thesheet-placed portion of the supply tray 20 from an upper side of therecording sheet 12. The supply rollers 25 are rotated in a secondrotational direction by receiving a driving power from a conveyor motor71 (as one example of a drive source, see FIGS. 3-5) rotating in itsreverse direction. As a result, the recording sheet 12 placed on thesupply tray 20 is supplied to a first conveyor roller 60 through a firstconveyance path 65 as one example of a main conveyance path. It is notedthat when the supply rollers 25 are rotated in the second rotationaldirection, the recording sheet 12 is conveyed in a first direction 15.Power transmission from the first conveyor roller 60 and the conveyormotor 71 to the supply rollers 25 will be explained later.

The first conveyance path 65 extends from a rear end portion of thesupply tray 20. The first conveyance path 65 includes a curved portionand a straight portion. The first conveyance path 65 is defined by anouter guide member 18 and an inner guide member 19 which are opposed toeach other at a predetermined distance therebetween. The recording sheet12 placed on the supply tray 20 is conveyed through the curved portionfrom its lower side toward upper side so as to make a U-turn. Therecording sheet 12 is then conveyed to a recording portion 24 (as oneexample of a recording device) through the straight portion. Therecording portion 24 performs image recording on the recording sheet 12.After the image recording, the recording sheet 12 is conveyed throughthe straight portion and discharged onto the output tray 21. That is,the recording sheet 12 is conveyed in the first direction 15 (as oneexample of a conveying direction) indicated by one-dot chain-line arrowin FIG. 2. It is noted that the recording portion 24 will be explainedlater in detail.

<First Conveyor Roller 60, Second Conveyor Rollers 62, and ThirdConveyor Rollers 45>

As illustrated in FIG. 2, a plurality of roller pairs are provided inthe first conveyance path 65. Specifically, a pair of the first conveyorroller 60 (as one example of a first roller) and pinch rollers 61 areprovided upstream of the recording portion 24 in the first direction 15.Also, a pair of a spur 63 and second conveyor rollers 62 (as one exampleof a second roller) are provided downstream of the recording portion 24in the first direction 15. Also, a pair of a spur 46 and third conveyorrollers 45 (as one example of a third roller) are provided downstream ofthe second conveyor rollers 62 in the first direction 15. Each of theroller pairs is rotated while nipping the recording sheet 12 to conveythe recording sheet 12.

The first conveyor roller 60 is rotated by a driving power transmittedfrom the conveyor motor 71. The conveyor motor 71 is rotatable in itsforward direction or reverse direction. When a driving power produced bythe forward rotation of the conveyor motor 71 is transmitted to thefirst conveyor roller 60, the first conveyor roller 60 is rotated in afirst rotational direction to convey the recording sheet 12 in the firstdirection 15. When a driving power produced by the reverse rotation ofthe conveyor motor 71 is transmitted to the first conveyor roller 60,the first conveyor roller 60 is rotated in the second rotationaldirection reverse to the first rotational direction to convey therecording sheet 12 in a direction opposite to the first direction 15.The first conveyor roller 60 transmits the power to the second conveyorrollers 62 and the third conveyor rollers 45 via a drive-powertransmitting mechanism 50 (see FIGS. 3-6) which will be described below.

It is noted that, in the present embodiment, the first conveyor roller60 contacts a recording face of the sheet conveyed through the firstconveyance path 65 (i.e., a face of the sheet on which an image isrecorded by the recording portion 24 which will be described below), andeach of the second conveyor rollers 62 and the third conveyor rollers 45contacts a face of the sheet which is on a back of the recording face.That is, when the first conveyor roller 60 is rotated in the firstrotational direction to convey the recording sheet 12 in the firstdirection 15, the second conveyor rollers 62 and the third conveyorrollers 45 are rotated in the second rotational direction. On the otherhand, when the first conveyor roller 60 is rotated in the secondrotational direction, each of the second conveyor rollers 62 and thethird conveyor rollers 45 is rotated in the first rotational direction.It is noted that, in FIG. 2, the first rotational direction is adirection in which each roller 60, 62, 45 is rotated in acounterclockwise direction, and the second rotational direction is adirection in which each roller 60, 62, 45 is rotated in a clockwisedirection.

In the duplex image recording, the conveying direction of the recordingsheet 12 conveyed through the first conveyance path 65 is switchedbetween the second conveyor rollers 62 and the third conveyor rollers 45such that the recording sheet 12 is conveyed to a second conveyance path67 which will be described below.

<Recording Portion 24>

As illustrated in FIG. 2, the recording portion 24 is provideddownstream of the first conveyor roller 60 and upstream of the secondconveyor rollers 62 in the first direction 15. A platen 42 is providedunder the recording portion 24 so as to be opposed to the recordingportion 24. The platen 42 supports the recording sheet 12 conveyedthrough the first conveyance path 65. The recording portion 24 employs awell-known ink-jet ejection method to record an image on the recordingsheet 12 supported on the platen 42. The recording portion 24 includes:a recording head 38 having a multiplicity of nozzles to eject inkdroplets onto the recording sheet 12 therethrough; and a carriage 40 forholding the recording head 38 mounted thereon.

The carriage 40 is supported by, e.g., a frame of the printing section11 so as to be reciprocable in main scanning directions that coincidewith the right and left directions 9 perpendicular to the front and reardirections 8. The carriage 40 is coupled to a carriage drive motor 53(see FIG. 9) by a well-known belt mechanism. Upon receipt of a drivingpower transmitted from the carriage drive motor 53, the carriage 40 isreciprocated in the right and left directions 9. This reciprocation ofthe carriage 40 is performed in a state in which the recording sheet 12is supported on the platen 42. The recording head 38 ejects ink dropletsin the reciprocation of the carriage 40. As a result, an image isrecorded on the recording sheet 12 supported on the platen 42. It isnoted that a method for recording an image on the recording sheet 12 bythe recording portion 24 is not limited to the ink-jet method and may bean electronic photographic method, for example.

<Sensor 160>

As illustrated in FIG. 2, a sensor 160 is provided in the firstconveyance path 65 at a position upstream of the first conveyor roller60 in the first direction 15. The sensor 160 includes: a shaft 161; adetector 162 pivotable about the shaft 161; and an optical sensor 163that includes a light emitting element and a light receiving element forreceiving light emitted from the light emitting element.

One end of the detector 162 projects into the first conveyance path 65.When an external force is not applied to the one end of the detector162, the other end of the detector 162 is located in a light pathextending from the light emitting element to the light receiving elementto interrupt the light traveling through the light path. In this state,the optical sensor 163 outputs a low-level signal to a controller 130which will be described below. When the one end of the detector 162 ispressed by a leading edge of the recording sheet 12 to rotate thedetector 162, the other end of the detector 162 is moved out of thelight path, causing the light to pass through the light path. In thisstate, the optical sensor 163 outputs a high-level signal to thecontroller 130. On the basis of the signal received from the opticalsensor 163, the controller 130 senses the leading edge and a trailingedge of the recording sheet 12 in the first direction 15.

<Rotary Encoder 73>

As illustrated in FIGS. 2-5, the first conveyor roller 60 is providedwith a rotary encoder 73 that produces a pulse signal in response to therotation of the first conveyor roller 60. The rotary encoder 73 includesan optical sensor 72 and an encoder disc 74 provided on a shaft 34 ofthe first conveyor roller 60 so as to be rotated along with the firstconveyor roller 60. The encoder disc 74 includes: light transmittingportions allowing light to pass therethrough; and light interceptingportions inhibiting the light from passing therethrough. These lighttransmitting portions and light intercepting portions are alternatelyarranged at regular pitches in a circumferential direction so as to forma predetermined pattern. The rotary encoder 73 produces a pulse signaleach time when the light transmitting portion and the light interceptingportion are sensed by the optical sensor 72 during the rotation of theencoder disc 74. The produced pulse signals are transmitted to thecontroller 130. The controller 130 detects a rotational amount of thefirst conveyor roller 60 on the basis of the pulse signals. As will bedescribed below, the conveyor rollers 60, 62, 45 are coupled to oneanother by belts. Thus, the controller 130 can also detect rotationalamounts of the second conveyor rollers 62 and the third conveyor rollers45 on the basis of the pulse signals.

<Path Switching Member 41 and Second Conveyance Path 67>

As illustrated in FIG. 2, a path switching member 41 as one example of aswitch mechanism is provided between the second conveyor rollers 62 andthe third conveyor rollers 45. The path switching member 41 includesauxiliary rollers 47, 48, a flap 49, and a shaft 87. The flap 49 ispivotably supported by the shaft 87 so as to extend from the shaft 87substantially in the first direction 15. The auxiliary rollers 47, 48each having a spur shape are provided respectively on shafts provided onthe flap 49.

The flap 49 is pivoted between (i) a discharge orientation indicated bybroken lines in FIG. 2 which allows the recording sheet 12 to bedischarged onto the output tray 21 and (ii) a flip orientation indicatedby solid lines in FIG. 2 in which a free end portion 49A of the flap 49is located at a position lower than that in the discharge orientation.

In a standby state of the MFP 10, the flap 49 is located at the fliporientation by its own weight. When the recording sheet 12 conveyedthrough the first conveyance path 65 comes into contact with the flap49, the flap 49 is moved upward so as to be pivoted to the dischargeorientation. The flap 49 (specifically, the auxiliary rollers 47, 48)thereafter guides the recording sheet 12 while contacting the recordingsheet 12. When an upstream edge, i.e., the trailing edge of therecording sheet 12 in the first direction 15 passes through theauxiliary roller 47, the flap 49 is pivoted by its own weight from thedischarge orientation to the flip orientation. As a result, the upstreamedge of the recording sheet 12 in the first direction 15 is moveddownward so as to be directed toward (i.e., so as to face or point) thesecond conveyance path 67 (as one example of a reverse conveyance path)which will be described below. When the third conveyor rollers 45continue to be rotated in the second rotational direction in this state,the recording sheet 12 is conveyed in the first direction 15 anddischarged onto the output tray 21. On the other hand, when a rotationaldirection of the third conveyor rollers 45 is switched to the firstrotational direction, the recording sheet 12 is conveyed in a directionopposite to the first direction 15 so as to enter into the secondconveyance path 67.

The second conveyance path 67 is branched from a position between thesecond conveyor rollers 62 and the third conveyor rollers 45 so as to bemerged with the first conveyance path 65 at a position upstream of thefirst conveyor roller 60 in the first direction 15. It is noted that thesecond conveyance path 67 is defined by guide members 31, 32.

<Fourth Conveyor Rollers 68>

As illustrated in FIG. 2, fourth conveyor rollers 68 as one example of afourth roller and a driven roller 69 are provided in the secondconveyance path 67. The fourth conveyor rollers 68 are disposed in thesecond conveyance path 67 at a position under and opposite to the drivenroller 69.

The driving power of the conveyor motor 71 is transmitted to the fourthconveyor rollers 68 via a fourth power transmitter 28 of the drive-powertransmitting mechanism 50 which will be described below. Upon receipt ofthe driving power, the fourth conveyor rollers 68 are rotated in such adirection that the recording sheet 12 is conveyed in a second direction16 along the second conveyance path 67. Specifically, the fourthconveyor rollers 68 are rotated only in the counterclockwise direction(i.e., the first rotational direction) in FIGS. 2 and 6. Here, thesecond direction 16 is a direction directed along the second conveyancepath 67 from the position between the second conveyor rollers 62 and thethird conveyor rollers 45 toward a position located upstream of thefirst conveyor roller 60 in the first direction 15. This seconddirection 16 is indicated by two-dot chain-line arrow in FIG. 2.

In view of the above, when the recording sheet 12 conveyed into thesecond conveyance path 67 by the third conveyor rollers 45 is nippedbetween the fourth conveyor rollers 68 and the driven roller 69, therecording sheet 12 is conveyed by the fourth conveyor rollers 68 in thesecond direction 16. As a result, the recording sheet 12 is delivered toa position located upstream of the first conveyor roller 60 in the firstdirection 15. Power transmission from the conveyor motor 71 to thefourth conveyor rollers 68 will be explained later.

<Drive-power Transmitting Mechanism 50>

As illustrated in FIGS. 3-5, the printing section 11 is provided withthe drive-power transmitting mechanism 50. The drive-power transmittingmechanism 50 includes a roller pulley 76, a motor pulley 58, a firstbelt 77, a first power transmitter 26, a second power transmitter 27, athird power transmitter 33, the fourth power transmitter 28, a supplypower transmitter 29, and a switcher 30. In the present embodiment, thesecond power transmitter 27 and the third power transmitter 33 are oneexample of a second power transmitter.

The drive-power transmitting mechanism. 50 causes the rollers 60, 62,45, 68, 25 to be rotated so as to convey the recording sheet 12 in theirrespective directions described in FIG. 8. That is, the drive-powertransmitting mechanism 50 causes the rollers 60, 62, 45, 68, 25 to berotated depending upon a position of a switch gear 51 of the switcher 30and the rotational direction of the conveyor motor 71. The rollers 60,62, 45, 68, 25 are rotated by the drive power transmitted from theconveyor motor 71 via any of the first power transmitter 26, the secondpower transmitter 27, the third power transmitter 33, the fourth powertransmitter 28, and the supply power transmitter 29. It is noted that inFIG. 8 each of the rollers 60, 62, 45, 68, 25 receives the rotationaldriving power from the conveyor motor 71 via a transmitter whose name isdescribed in corresponding parentheses.

As illustrated in FIG. 5, the roller pulley 76 is mounted on the shaft34 of the first conveyor roller 60 on a left side of the firstconveyance path 65. As illustrated in FIGS. 3-5, the motor pulley 58 ismounted on a rotation shaft of the conveyor motor 71. The endless firstbelt 77 is looped over the roller pulley 76 and the motor pulley 58. Asa result, the rotational driving power of the conveyor motor 71 istransmitted to the first conveyor roller 60. Specifically, when theconveyor motor 71 is rotated in the forward direction, the firstconveyor roller 60 is rotated in the first rotational direction, andwhen the conveyor motor 71 is rotated in the reverse direction, thefirst conveyor roller 60 is rotated in the second rotational direction.

<First Power Transmitter 26>

As illustrated in FIGS. 3-6, the first power transmitter 26 includes aleft gear 52, a lower gear 80, a first pulley 81, a second pulley 82,and a second belt 83. The left gear 52 is mounted on the shaft 34 of thefirst conveyor roller 60 on a left side of the first conveyance path 65.The lower gear 80 is provided under the left gear 52 so as to be inmeshed engagement with the left gear 52. The first pulley 81 is mountedon a right face of the lower gear 80 so as to be rotated coaxially andtogether with the lower gear 80. As a result, the first pulley 81 isrotated along with the rotation of the first conveyor roller 60. Thesecond pulley 82 is mounted on a shaft 64 of the second conveyor rollers62. The endless second belt 83 is looped over the first pulley 81 andthe second pulley 82. As a result, the rotation of the first conveyorroller 60 rotates the second belt 83, causing the rotational drivingpower of the first conveyor roller 60 to be transmitted to the secondconveyor rollers 62.

<Third Power Transmitter 33>

As illustrated in FIGS. 3-6, the third power transmitter 33 includes athird pulley 84, a fourth pulley 85, and a third belt 86. The thirdpulley 84 is mounted on the shaft 64 on a left side of the second pulley82 so as to be rotated coaxially and together with the second pulley 82.The fourth pulley 85 is mounted on a shaft 44 of the third conveyorrollers 45. The endless third belt 86 is looped over the third pulley 84and the fourth pulley 85. As a result, the rotational driving power ofthe second conveyor rollers 62 is transmitted to the third conveyorrollers 45. That is, the third conveyor rollers 45 are rotated with therotation of the second conveyor rollers 62 by receiving the rotationaldriving power from the second conveyor rollers 62.

In the following explanation, each of the clockwise direction, i.e., thesecond rotational direction and the counterclockwise direction, i.e.,the first rotational direction is a rotational direction of each rollerand each gear in FIG. 6. That is, each of the clockwise direction andthe counterclockwise direction is a rotational direction of each rollerand each gear when each roller and each gear are seen from the leftside. Accordingly, it is to be understood that, when each roller andeach gear are seen from the right side, for example, the clockwisedirection and the counterclockwise direction respectively coincide withthe first rotational direction and the second rotational direction. Awell-known one-way clutch (specifically, a needle clutch) is providedinside the second pulley 82. That is, the second pulley 82 is mounted onthe shaft 64 via the one-way clutch. As a result, as illustrated in FIG.6, in the present embodiment, when the conveyor motor 71 is rotated inthe forward direction, the shaft 64 is rotated in the clockwisedirection, i.e., the second rotational direction, but when the conveyormotor 71 is rotated in the reverse direction, the shaft 64 is notrotated. Accordingly, when the conveyor motor 71 is rotated in theforward direction, the forward rotational driving power is transmittedto the conveyor rollers 60, 62, 45, causing the conveyor rollers 60, 62,45 to be rotated so as to convey the recording sheet 12 in the firstdirection 15. Specifically, in the present embodiment, the firstconveyor roller 60 is rotated in the counterclockwise direction, i.e.,the first rotational direction, and each of the second conveyor rollers62 and the third conveyor rollers 45 is rotated in the clockwisedirection, i.e., the second rotational direction. On the other hand,when the conveyor motor 71 is rotated in the reverse direction, thereverse rotational driving power is transmitted to the first conveyorroller 60, but the second pulley 82 slips on the shaft 64 by the one-wayclutch. Thus, the reverse rotational driving power is not transmitted tothe second conveyor rollers 62. As a result, only the first conveyorroller 60 is rotated in the clockwise direction, i.e., the secondrotational direction so as to convey the recording sheet 12 in thedirection opposite to the first direction 15, and the second conveyorrollers 62 and the third conveyor rollers 45 are not rotated.

<Second Power Transmitter 27>

As illustrated in FIGS. 3-6, the second power transmitter 27 includes: afirst gear 78 as one example of a first roller gear; a second gear 101as one example of a drive mechanism or a second roller gear; a firstoutput gear 75; a plurality of first intermediate gears 95 (as oneexample of a transmitter unit) meshed with one another; and a firstplanetary gear mechanism 96. The first planetary gear mechanism 96includes: a sun gear 97 meshed with a frontmost one of the firstintermediate gears 95; a planetary gear 98 rotatable while revolvingaround the sun gear 97; and an arm 102.

The first gear 78 is provided on the shaft 34 of the first conveyorroller 60 on a right side of the first conveyance path 65. When thefirst conveyor roller 60 is rotated, the first gear 78 is also rotated.That is, the first gear 78 is provided coaxially with the first conveyorroller 60 and rotated together with the first conveyor roller 60. As aresult, the rotational driving power is transmitted from the first gear78 to the first output gear 75 via the switch gear 51 of the switcher 30which will be described below.

The first output gear 75 is in meshed engagement with: the switch gear51; a rearmost one of the first intermediate gears 95; and a sun gear109 of a second planetary gear mechanism 103 of the fourth powertransmitter 28 which will be described below. It is noted that, as willbe described below, when the switch gear 51 is located at a second powertransmission position, the first output gear 75 is meshed with theswitch gear 51, so that the rotational driving power is transmitted fromthe first gear 78 to the first output gear 75 (see FIG. 7B).

The first intermediate gears 95 are arranged substantially in the frontand rear directions 8 in a state in which the first intermediate gears95 are meshed with one another. In the present embodiment, an evennumber of the first intermediate gears 95 are arranged. It is to beunderstood that, while the four first intermediate gears 95 areillustrated in FIG. 6, the number of the first intermediate gears 95 isnot limited to four. The frontmost first intermediate gear 95 is meshedwith the sun gear 97 of the first planetary gear mechanism 96. In viewof the above, the rotational driving power of the first gear 78 istransmitted to the sun gear 97 via the first output gear 75 and thefirst intermediate gears 95.

The sun gear 97 is rotatably supported by, e.g., the frame of theprinting section 11. The sun gear 97 has a thrust face on which one endof the arm 102 is mounted. As a result, the arm 102 is rotated coaxiallywith the sun gear 97. The planetary gear 98 is rotatably supported onthe other end of the arm 102. The planetary gear 98 is in meshedengagement with the sun gear 97. Thus, the planetary gear 98 is rotatedwhile supported by the arm 102 and is revolved in a rotational directionof the sun gear 97 while meshed with the sun gear 97.

There will be next explained power transmission of the second powertransmitter 27 with reference to FIG. 6. When the conveyor motor 71 (seeFIGS. 3-5) is rotated in the reverse direction, each of the firstconveyor roller 60 and the first gear 78 is rotated in the clockwisedirection, i.e., the second rotational direction. Here, the switch gear51, the first output gear 75, and the even number of the firstintermediate gears 95 are provided between the first gear 78 and the sungear 97, that is, an even number of gears are arranged in series betweenthe first gear 78 and the sun gear 97 in a state in which these gearsare meshed with one another. Thus, when the first gear 78 is rotated inthe clockwise direction, the sun gear 97 is rotated in thecounterclockwise direction, i.e., in a direction indicated by arrow 99.

When the sun gear 97 is rotated in the counterclockwise direction, theplanetary gear 98 is revolved around the sun gear 97 in the directionindicated by arrow 99. As a result, the planetary gear 98 is connectedto and meshed with the second gear 101. Here, the second gear 101 isprovided on a right end portion of the shaft 64 of the second conveyorrollers 62 (see FIGS. 3-5) and rotated together with the second conveyorrollers 62. When the planetary gear 98 and the second gear 101 areconnected to and meshed with each other, the planetary gear 98 stopsrevolving and starts rotating. A direction of the rotation of theplanetary gear 98 is the clockwise direction. Thus, when the planetarygear 98 is rotated, the second gear 101 connected to and meshed with theplanetary gear 98, i.e., the second conveyor rollers 62 are rotated inthe counterclockwise direction, i.e., the first rotational direction,that is, the second conveyor rollers 62 are rotated in the direction inwhich the recording sheet 12 is conveyed in the direction opposite tothe first direction 15.

The rotational driving power of the second conveyor rollers 62 in thecounterclockwise direction, i.e., the first rotational direction istransmitted to the third conveyor rollers 45 via the third pulley 84,the third belt 86, and the fourth pulley 85. As a result, the thirdconveyor rollers 45 are also rotated in the counterclockwise direction,i.e., the first rotational direction, that is, the third conveyorrollers 45 are also rotated in the direction in which the recordingsheet 12 is conveyed in the direction opposite to the first direction15.

On the other hand, when the conveyor motor 71 is rotated in the forwarddirection, the first gear 78 and the sun gear 97 are rotated in theclockwise direction in contrast to the above-described case. Thus, theplanetary gear 98 is revolved around the sun gear 97 in a directionindicated by arrow 100. As a result, the planetary gear 98 isdisconnected from the second gear 101. Thus, the second powertransmitter 27 does not cause the rotations of the second conveyorrollers 62 and the third conveyor rollers 45.

In view of the above, the second power transmitter 27 transmits therotational driving power of the first conveyor roller 60 in the secondrotational direction (as one example of a second-direction drivingpower) to the second conveyor rollers 62. On the other hand, the secondpower transmitter 27 does not transmit the rotational driving power ofthe first conveyor roller 60 in the first rotational direction (as oneexample of a first-direction driving power) to the second conveyorrollers 62.

It is noted that, when the conveyor motor 71 is rotated in the forwarddirection, the forward rotational driving power of the conveyor motor 71is transmitted to the second conveyor rollers 62 by the first powertransmitter 26 and to the third conveyor rollers 45 by the third powertransmitter 33 as described above. Thus, when the conveyor motor 71 isrotated in the forward direction, the conveyor rollers 60, 62, 45 arerotated so as to convey the recording sheet 12 in the first direction15. That is, the first conveyor roller 60 is rotated in thecounterclockwise direction, i.e., the first rotational direction, andthe second conveyor rollers 62 and the third conveyor rollers 45 arerotated in the clockwise direction, i.e., the second rotationaldirection.

In the second power transmitter 27, the first intermediate gears 95 asone example of a speed reducer reduce a rotational speed of the firstgear 78 and transmit the speed-reduced rotational power to the sun gear97. To reduce the rotational speed of the first gear 78, for example,the first intermediate gears 95 are designed as described below indetail in the present embodiment. It is noted that the first gear 78 isnot limited to the gear designed as described below in detail, and therotational speed of the first gear 78 may be reduced by employing awell-known gear.

In the present embodiment, a gear pitch (i.e., a distance between teeth)of one of the first intermediate gears 95 is larger than that of theother gears of the second power transmitter 27. Thus, the rotationalspeed of the first gear 78 is reduced at the one of the firstintermediate gears 95 with the large gear pitch, resulting in a reducedrotational speed of the second conveyor rollers 62 to which therotational driving power is transmitted via the first intermediate gears95.

<Fourth Power Transmitter 28>

As illustrated in FIGS. 3-6, the fourth power transmitter 28 includes:the second planetary gear mechanism 103; a forward-rotation meshing gear104; a reverse-rotation meshing gear 105; a plurality of secondintermediate gears 106 meshed with one another; third intermediate gears107; and a third gear 108. The second planetary gear mechanism 103includes: the sun gear 109 meshed with the first output gear 75; twoplanetary gears 110, 111 each rotatable while revolving around the sungear 109; and two arms 112, 113.

The sun gear 109 is rotatably supported by, e.g., the frame of theprinting section 11. The sun gear 109 is rotated by the driving powertransmitted from the first output gear 75 of the second powertransmitter 27. That is, as in the case of the second power transmitter27, the fourth power transmitter 28 receives the driving power from thefirst gear 78 when the switch gear 51 is located at the second powertransmission position (see FIG. 7B).

The sun gear 109 has a thrust face on which one ends of the arms 112,113 are mounted. Thus, the arms 112, 113 are rotated coaxially with thesun gear 109. The planetary gear 110 is rotatably supported on the otherend of the arm 112. The planetary gear 111 is rotatably supported on theother end of the arm 113. The planetary gears 110, 111 are in meshedengagement with the sun gear 109. In the construction described above,the planetary gear 110 is rotated while supported by the arm 112 and isrevolved in a rotational direction of the sun gear 109 while meshed withthe sun gear 109. Also, the planetary gear 111 is rotated whilesupported by the arm 113 and is revolved in a rotational direction ofthe sun gear 109 while meshed with the sun gear 109.

The planetary gear 110 is meshable with the forward-rotation meshinggear 104. The planetary gear 111 is meshable with the reverse-rotationmeshing gear 105. The reverse-rotation meshing gear 105 is in meshedengagement with the forward-rotation meshing gear 104. In addition tothe reverse-rotation meshing gear 105, the forward-rotation meshing gear104 is in meshed engagement with a rearmost one of the secondintermediate gears 106.

The second intermediate gears 106 are arranged substantially in thefront and rear directions 8 in a state in which the second intermediategears 106 are meshed with one another. In the present embodiment, aneven number of the second intermediate gears 106 are arranged. It is tobe understood that, while the four second intermediate gears 106 areillustrated in FIG. 6, the number of the second intermediate gears 106is not limited to four. The third intermediate gears 107 are providedcoaxially with a frontmost one of the second intermediate gears 106. Thethird intermediate gears 107 are rotated about a shaft 79 together withthe frontmost second intermediate gear 106. The third intermediate gears107 are in meshed engagement with the third gear 108. The third gear 108is disposed coaxially with the fourth conveyor rollers 68 so as to berotatable together with the fourth conveyor rollers 68.

There will be next explained power transmission of the fourth powertransmitter 28 with reference to FIG. 6. When the conveyor motor 71 isrotated in the forward direction, the first conveyor roller 60 and thefirst gear 78 are rotated in the counterclockwise direction, i.e., thefirst rotational direction, the switch gear 51 is rotated in theclockwise direction, and the first output gear 75 is rotated in thecounterclockwise direction. The sun gear 109 is in turn rotated in theclockwise direction, i.e., in a direction indicated by arrow 114. As aresult, the arms 112, 113 are also rotated in the direction indicated byarrow 114. Thus, the planetary gear 110 is meshed with theforward-rotation meshing gear 104, and the planetary gear 111 isdisconnected or moved away from the reverse-rotation meshing gear 105.The planetary gear 111 meshed with the forward-rotation meshing gear 104is rotated in the counterclockwise direction, whereby theforward-rotation meshing gear 104 is rotated in the clockwise direction.

Here, the even number of the second intermediate gears 106 are arrangedin series between the forward-rotation meshing gear 104 and the thirdgear 108 in a state in which these gears are meshed with one another. Itis noted that since the third intermediate gears 107 are rotatedcoaxially and together with the second intermediate gears 106, thenumber of the third intermediate gears 107 is not included in theabove-described number of the second intermediate gears 106. In view ofthe above, when the forward-rotation meshing gear 104 is rotated in theclockwise direction, the third gear 108 and the fourth conveyor rollers68 are rotated in the counterclockwise direction. That is, when theconveyor motor 71 is rotated in the forward direction, the fourthconveyor rollers 68 are rotated in the counterclockwise direction, i.e.,the first rotational direction.

On the other hand, when the conveyor motor 71 is rotated in the reversedirection, each of the first conveyor roller 60 and the first gear 78 isrotated in the clockwise direction, i.e., the second rotationaldirection, the switch gear 51 is rotated in the counterclockwisedirection, and the first output gear 75 is rotated in the clockwisedirection. The sun gear 109 is in turn rotated in the counterclockwisedirection, i.e., in a direction indicated by arrow 115. As a result, thearms 112, 113 are also rotated in the direction indicated by arrow 115.Thus, the planetary gear 110 is disconnected or moved away from theforward-rotation meshing gear 104, and the planetary gear 111 is meshedwith the reverse-rotation meshing gear 105. The planetary gear 111meshed with the reverse-rotation meshing gear 105 is rotated in theclockwise direction, whereby the reverse-rotation meshing gear 105 isrotated in the counterclockwise direction.

Here, the forward-rotation meshing gear 104 and the even number of thesecond intermediate gears 106 are arranged between the reverse-rotationmeshing gear 105 and the third gear 108, that is, an odd number of gearsare arranged in series between the reverse-rotation meshing gear 105 andthe third gear 108 in a state in which these gears are meshed with oneanother. In view of the above, when the reverse-rotation meshing gear105 is rotated in the counterclockwise direction, the third gear 108 andthe fourth conveyor rollers 68 are also rotated in the counterclockwisedirection. That is, even when the conveyor motor 71 is rotated in thereverse direction, the fourth conveyor rollers 68 are rotated in thecounterclockwise direction, i.e., the first rotational direction.

In view of the above, the fourth power transmitter 28 transmits theforward and reverse rotational driving powers of the first conveyorroller 60, i.e., both of the rotational driving power in thecounterclockwise direction and the rotational driving power in theclockwise direction, to the fourth conveyor rollers 68 as the rotationaldriving power for conveying the recording sheet 12 in the seconddirection 16, i.e., the rotational driving power in the first rotationaldirection.

The fourth power transmitter 28 increases a rotational speed of thefirst conveyor roller 60 in the counterclockwise direction, i.e., thefirst rotational direction and transmits the speed-increased rotationalpower to the fourth conveyor rollers 68. To increase the speed, forexample, the fourth power transmitter 28 is designed as described belowin detail in the present embodiment. It is noted that the fourth powertransmitter 28 is not limited to have the construction as describedbelow in detail, and the rotational speed of the first conveyor roller60 may be increased by employing a well-known construction.

In the present embodiment, gear ratios of the gears of the fourth powertransmitter 28 are set such that the fourth conveyor rollers 68 arerotated faster than the conveyor rollers 60, 62, 45. It is noted thatthe reverse-rotation meshing gear 105 is used for power transmissiononly when the first conveyor roller 60 is rotated in the clockwisedirection, and a gear pitch (i.e., a distance between teeth) of thisreverse-rotation meshing gear 105 is larger than that of the other gearsof the fourth power transmitter 28. This pitch is set such that thefourth conveyor rollers 68 are rotated at the same speed as the conveyorrollers 60, 62, 45 when the first conveyor roller 60 is rotated in theclockwise direction.

In view of the above, the fourth conveyor rollers 68 receiving thedriving power via the fourth power transmitter 28 are rotated at thesame speed as the conveyor rollers 60, 62, 45 when the first conveyorroller 60 is rotated in the clockwise direction. On the other hand, whenthe first conveyor roller 60 is rotated in the counterclockwisedirection, the fourth conveyor rollers 68 are rotated faster than theconveyor rollers 60, 62, 45. Among the gears of the fourth powertransmitter 28, the gears used for the increase in speed are one exampleof a speed increasing mechanism.

<Supply Power Transmitter 29>

As illustrated in FIGS. 3-6, the supply power transmitter 29 includes: asecond output gear 88; fourth intermediate gears 89; a fourth belt 90;two fifth intermediate gears 91; a sixth intermediate gear 92 mounted ona shaft 93; a third planetary gear mechanism 120; a seventh intermediategear 121; an eighth intermediate gear 122; a fifth belt 94; and a supplypulley 123 provided coaxially with the supply rollers 25. The thirdplanetary gear mechanism 120 includes: a sun gear 124 rotatable aboutand together with the shaft 93; a planetary gear 125 rotatable whilerevolving around the sun gear 124; and an arm 126.

The second output gear 88 is in meshed engagement with a rear one of thefourth intermediate gears 89. As will be described below, when theswitch gear 51 is located at a first power transmission position, thesecond output gear 88 is meshed with the switch gear 51, so that therotational driving power is transmitted from the first gear 78 to thesecond output gear 88 (see FIG. 7A). In the present embodiment, an evennumber of the fourth intermediate gears 89 (specifically, two fourthintermediate gears 89) are provided. A front one of the fourthintermediate gears 89 is disposed coaxially with a rear one of the twofifth intermediate gears 91.

The endless fourth belt 90 is looped over the two fifth intermediategears 91. Specifically, the fourth belt 90 is disposed adjacent to thetwo fifth intermediate gears 91 and looped over two pulleys that arerespectively rotated coaxially and together with the fifth intermediategears 91.

A front one of the two fifth intermediate gears 91 is in meshedengagement with the sixth intermediate gear 92. The sixth intermediategear 92 and the sun gear 124 of the third planetary gear mechanism 120are rotated about and together with the shaft 93. The sun gear 124 has athrust face on which one end of the arm 126 is mounted. Thus, the arm126 is rotated about the shaft 93. The planetary gear 125 is rotatablysupported on the other end of the arm 126. The planetary gear 125 is inmeshed engagement with the sun gear 124. In the construction describedabove, the planetary gear 125 is rotated while supported by the arm 126and is revolved around the sun gear 124 in a rotational direction of thesun gear 124 while meshed with the sun gear 124.

The seventh intermediate gear 121 is disposed at a position at which theseventh intermediate gear 121 is meshable with the planetary gear 125.The eighth intermediate gear 122 is in meshed engagement with theseventh intermediate gear 121. The endless fifth belt 94 is looped overthe supply pulley 123 and the eighth intermediate gear 122(specifically, a pulley disposed adjacent to the eighth intermediategear 122 and rotatable coaxially and together with the eighthintermediate gear 122). It is noted that the supply rollers 25 and thesupply pulley 123 are rotated coaxially and together with each other.

There will be next explained power transmission of the supply powertransmitter 29 with reference to FIG. 6. When the conveyor motor 71 isrotated in the reverse direction, each of the first conveyor roller 60and the first gear 78 is rotated in the clockwise direction, i.e., thesecond rotational direction. When the first gear 78 is rotated in theclockwise direction, the switch gear 51 is rotated in thecounterclockwise direction, the second output gear 88 is rotated in theclockwise direction, the fourth intermediate gears 89 are rotated in thecounterclockwise direction, and the two fifth intermediate gears 91 arerotated in the clockwise direction.

When the fifth intermediate gears 91 are rotated in the clockwisedirection, the sixth intermediate gear 92 and the sun gear 124 providedcoaxially with the sixth intermediate gear 92 are rotated in thecounterclockwise direction. When the sun gear 124 is rotated in thecounterclockwise direction, i.e., in a direction indicated by arrow 127,the planetary gear 125 is revolved around the sun gear 124 in thedirection indicated by arrow 127. As a result, the planetary gear 125 isconnected to and meshed with the seventh intermediate gear 121. When theplanetary gear 125 and the seventh intermediate gear 121 are connectedto and meshed with each other, the planetary gear 125 stops revolvingand starts rotating. A direction of the rotation of the planetary gear125 is the clockwise direction. Thus, when the planetary gear 125 isrotated, the seventh intermediate gear 121 meshed with the planetarygear 125 is rotated in the counterclockwise direction.

When the seventh intermediate gear 121 is rotated in thecounterclockwise direction, the eighth intermediate gear 122 and thesupply pulley 123 are rotated in the clockwise direction. When thesupply pulley 123 is rotated in the clockwise direction, the supplyrollers 25 are also rotated in the clockwise direction, i.e., the secondrotational direction. When the supply rollers 25 are rotated in theclockwise direction, i.e., the second rotational direction, therecording sheet 12 placed on the supply tray 20 and contacting thesupply rollers 25, i.e., an uppermost one of the recording sheets 12placed on the supply tray 20 is supplied toward the first conveyorroller 60.

On the other hand, when the conveyor motor 71 is rotated in the forwarddirection, the sun gear 124 is rotated in the clockwise direction, i.e.,in a direction indicated by arrow 128 in contrast to the case where theconveyor motor 71 is rotated in the reverse direction. Thus, theplanetary gear 125 is revolved around the sun gear 124 in the directionindicated by arrow 128. As a result, the planetary gear 125 isdisconnected or moved away from the seventh intermediate gear 121. Inview of the above, when the conveyor motor 71 is rotated in the forwarddirection, the rotational driving power is not transmitted from theconveyor motor 71 to the supply rollers 25, not causing the rotation ofthe supply rollers 25.

<Switcher 30>

As illustrated in FIGS. 3-7B, the switcher 30 includes the switch gear51, coil springs 56, 57, and a switch lever 55 as one example of acontact member.

As illustrated in FIGS. 7A and 7B, the switch gear 51 is in meshedengagement with the first gear 78. Thus, the switch gear 51 is rotatedby the driving power transmitted from the conveyor motor 71. The switchgear 51 is movable in the right and left directions 9 at least betweenthe first power transmission position (as one example of a firstposition) indicated in FIG. 7A and the second power transmissionposition (as one example of a second position) indicated in FIG. 7B in astate in which the switch gear 51 is meshed with the first gear 78. Thefirst power transmission position is located on a left side of thesecond power transmission position. Each of the first power transmissionposition and the second power transmission position is located on aright side of the first conveyance path 65.

As illustrated in FIG. 7A, when the switch gear 51 is located at thefirst power transmission position, the switch gear 51 is connected to(i.e., meshed with) the first gear 78 and the fourth intermediate gear89. It is noted that the switch gear 51 is not meshed with the firstoutput gear 75 in this state. As a result, the rotational driving powertransmitted from the conveyor motor 71 to the switch gear 51 via thefirst gear 78 is transmitted to the supply power transmitter 29.

As illustrated in FIG. 7B, when the switch gear 51 is located at thesecond power transmission position, the switch gear 51 is connected to(i.e., meshed with) the first gear 78 and the first output gear 75. Itis noted that the switch gear 51 is not meshed with the fourthintermediate gear 89 in this state. As a result, the rotational drivingpower transmitted from the conveyor motor 71 to the switch gear 51 viathe first gear 78 is transmitted to the second power transmitter 27 andthe fourth power transmitter 28.

As illustrated in FIGS. 7A and 7B, a right face of the switch gear 51 iscontactable with the switch lever 55. The carriage 40 of the recordingportion 24 is contactable with the switch lever 55 from the left side.Also, the switch lever 55 is provided with the coil spring 56. Theswitch lever 55 and the coil spring 56 are arranged along an axialdirection of the switch gear 51. One end of the coil spring 56 ismounted on a right face of the switch lever 55, and the other end of thecoil spring 56 is mounted on, e.g., the frame of the printing section11, not shown. As a result, the switch lever 55 is urged by the coilspring 56 from a side nearer to the second power transmission positiontoward a side nearer to the first power transmission position, i.e., ina leftward direction. Also, the coil spring 57 is mounted on the switchgear 51 on an opposite side thereof from the coil spring 56. As aresult, the switch gear 51 is urged by the coil spring 57 from the sidenearer to the first power transmission position toward the side nearerto the second power transmission position, i.e., in a rightwarddirection. It is noted that an urging force of the coil spring 56 isgreater than that of the coil spring 57. Therefore, the switch gear 51and the switch lever 55 are urged from the side nearer to the secondpower transmission position toward the side nearer to the first powertransmission position, i.e., in the leftward direction.

The switch gear 51 located at the first power transmission position isinhibited by a stopper, not shown, from being moved by the urging forceof the coil spring 56 from the second power transmission position towardthe first power transmission position, i.e., in the leftward direction.This keeps the switch gear 51 at the first power transmission position.When the switch gear 51 located at the first power transmission positionis pushed by the carriage 40 so as to be moved rightward from the firstpower transmission position, the switch gear 51 is released from thestopper and moved from the first power transmission position (see FIG.7A) to the second power transmission position (see FIG. 7B). It is notedthat the stopper is designed to inhibit or stop the leftward movement ofthe switch gear 51 at the first power transmission position and thesecond power transmission position but also designed not to inhibit orstop the rightward movement of the switch gear 51 at the first powertransmission position and the second power transmission position.

As in the case of the switch gear 51 located at the first powertransmission position, the switch gear 51 located at the second powertransmission position is inhibited by a stopper, not shown, (having aconstruction similar to that of the stopper provided at the first powertransmission position) from being moved by the urging force of the coilspring 56 from the second power transmission position toward the firstpower transmission position, i.e., in the leftward direction. This keepsthe switch gear 51 at the second power transmission position.

When the switch gear 51 located at the second power transmissionposition is pushed by the carriage 40 so as to be moved rightward fromthe second power transmission position, the switch gear 51 is releasedfrom the stopper. When the carriage 40 is moved leftward in this state,the switch gear 51 is moved by the urging force of the coil spring 56from the second power transmission position to the first powertransmission position.

In view of the above, the switcher 30 selectively switches the powertransmission from the first conveyor roller 60 to the second powertransmitter 27 and the fourth power transmitter 28, or the supply powertransmitter 29. Specifically, when the switch gear 51 is located at thesecond power transmission position, the switcher 30 transmits thedriving power from the first conveyor roller 60 to the second powertransmitter 27 and the fourth power transmitter 28. On the other hand,when the switch gear 51 is located at the first power transmissionposition, the switcher 30 does not transmit the driving power from thefirst conveyor roller 60 to the second power transmitter 27. It is notedthat, when the switch gear 51 is located at the first power transmissionposition, the switcher 30 transmits the driving power from the firstconveyor roller 60 to the supply power transmitter 29.

<Controller 130>

The controller 130 illustrated in FIG. 9 controls overall operations ofthe MFP 10. For example, the controller 130 controls the conveyor motor71. The controller 130 also controls the carriage drive motor 53 to movethe carriage 40 in order to control the switcher 30 to switch thetransmission of the driving power. As illustrated in FIG. 9, thecontroller 130 includes a CPU 131, a ROM 132, a RAM 133, an EEPROM 134,an ASIC 135, and an internal bus 137 for connecting these devices to oneanother.

The ROM 132 stores various programs and data for the CPU 131 to controlvarious operations. The RAM 133 is used as a storage area fortemporarily storing, e.g., data and signals used when the CPU 131executes the programs. The EEPROM 134 is for storing settings, flags,and other similar data which should be kept after the MFP 10 is turnedoff.

Connected to the ASIC 135 are the conveyor motor 71 and the carriagedrive motor 53. When a drive signal for rotating each motor is inputfrom the CPU 131 to a corresponding drive circuit, a drive currentrelated to the drive signal is output from the drive circuit to themotor, causing the motor to be rotated forwardly or reversely at apredetermined rotational speed.

Also, a pulse signal output from the optical sensor 72 of the rotaryencoder 73 is input to the ASIC 135. On the basis of this pulse signaltransmitted from the optical sensor 72, the controller 130 detectsrotational amounts of the conveyor rollers 60, 62, 45.

Also, the optical sensor 163 of the sensor 160 is connected to the ASIC135. On the basis of a signal transmitted from the optical sensor 163,the controller 130 detects a downstream edge (i.e., a leading edge) andan upstream edge (a trailing edge) of the recording sheet 12 in thefirst direction 15 at the position of the sensor 160.

<Controls of Controller 130>

There will be next explained, with reference to the flow chart in FIG.10, a procedure of processings executed by the controller 130 forsimplex image recording and duplex image recording on the recordingsheet 12. It is noted that a control for conveying the recording sheet12 is mainly explained in FIG. 10. Also, an initial position of theswitcher 30 is the first power transmission position in the flow in FIG.10.

When a command for image recording on the recording sheet 12 is input tothe MFP 10 from, e.g., an operation panel 17 (see FIG. 1), thecontroller 130 at S10 determines whether the command is for the simpleximage recording or the duplex image recording.

<Simplex Image Recording>

When the command is for the simplex image recording (S10: No), thecontroller 130 at S20 rotates the conveyor motor 71 in the reversedirection. This rotation causes the supply rollers 25 to be rotated inthe clockwise direction, i.e., the second rotational direction in FIGS.2 and 6. As a result, the recording sheet 12 placed on the supply tray20 is supplied by the supply rollers 25 from the supply tray 20 towardthe first conveyor roller 60 so as to be conveyed in the first direction15 along the first conveyance path 65.

Also, when the conveyor motor 71 is rotated in the reverse direction,the first conveyor roller 60 are rotated in the clockwise direction,i.e., the second rotational direction in FIGS. 2 and 6. When the leadingedge of the recording sheet 12 in the first direction 15 reaches thefirst conveyor roller 60, the leading edge comes into contact with thefirst conveyor roller 60 rotating in the clockwise direction, i.e., thesecond rotational direction, whereby oblique conveyance of the recordingsheet 12 is corrected.

The controller 130 at S30 rotates the conveyor motor 71 in the reversedirection by a first rotational amount. Here, the first rotationalamount is set at an amount enough for the leading edge of the recordingsheet 12 in the first direction 15 to be conveyed from the supply tray20 to the first conveyor roller 60. Thus, when the conveyor motor 71 isrotated in the reverse direction by the first rotational amount, therecording sheet 12 is sensed by the sensor 160.

When the conveyor motor 71 is rotated in the reverse direction by thefirst rotational amount (S30: Yes), the controller 130 at 540 switchesthe rotational direction of the conveyor motor 71 from the reversedirection to the forward direction. As a result, the supply rollers 25are stopped, and the conveyor rollers 60, 62, 45 are rotated in theirrespective directions to convey the recording sheet 12 in the firstdirection 15. As a result, the recording sheet 12 is conveyed in thefirst direction 15 by the conveyor rollers 60, 62, 45 along the firstconveyance path 65. It is noted that at S40 the first conveyor roller 60is rotated in the counterclockwise direction, i.e., the first rotationaldirection, and the second conveyor rollers 62 and the third conveyorrollers 45 are rotated in the clockwise direction, i.e., the secondrotational direction.

The controller 130 at S60 rotates the conveyor motor 71 in the forwarddirection by a second rotational amount. In the present embodiment, thesecond rotational amount is set at an amount enough for the recordingportion 24 to complete the image recording on the recording sheet 12.Specifically, the second rotational amount is set at an amount enoughfor the trailing edge of the recording sheet 12 in the first direction15 to be conveyed from the first conveyor roller 60 and then passthrough the position just under the recording portion 24. Thus, beforethe conveyor motor 71 has been rotated by the second rotational amountin the forward direction, the trailing edge of the recording sheet 12 inthe first direction 15 passes through the sensor 160. As a result, thesensor 160 ceases sensing the recording sheet 12 (S50: Yes). Also,before the conveyor motor 71 has been rotated by the second rotationalamount in the forward direction, the trailing edge of the recordingsheet 12 in the first direction 15 passes through the first conveyorroller 60. It is noted that the controller 130 in the image recordingalternately executes a recording processing for reciprocating therecording portion 24 in the right and left directions 9 and a conveyanceprocessing for conveying the recording sheet 12 after the recordingprocessing. Accordingly, the second rotational amount is a sum ofrotational amounts in respective conveyance processings in the imagerecording.

When the image recording on the recording sheet 12 is completed, thecontroller 130 at S70 determines, based on the image recording command,whether there is a next page for image recording or not. When there is anext page (S70: Yes), the controller 130 at S80 switches the rotationaldirection of the conveyor motor 71 from the forward direction to thereverse direction. As a result, the second conveyor rollers 62 and thethird conveyor rollers 45 are stopped. Also, the supply rollers 25 andthe first conveyor roller 60 are rotated in the clockwise direction,i.e., the second rotational direction. As a result, the recording sheet12 placed on the supply tray 20 is supplied by the supply rollers 25from the supply tray 20 to the first conveyance path 65 and conveyed inthe first direction 15 along the first conveyance path 65.

The controller 130 at S90 rotates the conveyor motor 71 in the reversedirection by a third rotational amount. Here, the third rotationalamount is set at the same amount as the first rotational amount in thepresent embodiment but may differ from the first rotational amount. As aresult, a subsequent recording sheet 12 supplied at S80 is conveyed tothe first conveyor roller 60. Here, since the first conveyor roller 60are being rotated in the clockwise direction, i.e., the secondrotational direction, the recording sheet 12 supplied at S80 does notpass through the first conveyor roller 60. Also, since the secondconveyor rollers 62 and the third conveyor rollers 45 are stopped, theprior recording sheet 12 supplied at S20 is kept stopped.

Executing the processings at S70-S90 allows the subsequent recordingsheet 12 to be conveyed to a position just upstream of the recordingportion 24 at a relatively early timing. This makes it possible toreduce a length of time required for a series of processings from thesupply of the prior recording sheet 12 to the discharge of the priorsheet 12 after the image recording.

After the processing at S90, the processings at S40-S90 are repeateduntil the controller 130 at S70 determines that there is no next page(S70: No). The processings at S20-S90 are one example of a firstcontrol.

When the controller 130 at S70 determines that there is no next page(S70: No), the controller 130 at S100 continues rotating the conveyormotor 71 in the forward direction (noted that this forward rotation iscontinued from the processing at S40). As a result, the recording sheet12 is conveyed by the second conveyor rollers 62 and the third conveyorrollers 45 in the first direction 15 along the first conveyance path 65.

The controller 130 at S120 rotates the conveyor motor 71 in the forwarddirection by a discharge rotational amount. Here, the dischargerotational amount is set at an amount enough for the recording sheet 12to be discharged onto the output tray 21. When the conveyor motor 71 isrotated in the forward direction by the discharge rotational amount, therecording sheet 12 is discharged onto the output tray 21.

<Duplex Image Recording>

On the other hand, when the image recording command is for the dupleximage recording (S10: Yes), the controller 130 at S120 rotates theconveyor motor 71 in the reverse direction. In the present embodiment,processings at S120-S160 are respectively similar to those at S20-S60.It is noted that a fourth rotational amount is the same amount as thefirst rotational amount in the present embodiment but may differ fromthe first rotational amount. In the present embodiment, a fifthrotational amount is set at an amount larger than the second rotationalamount. Specifically, the fifth rotational amount is set at an amountenough not only for the trailing edge of the recording sheet 12 in thefirst direction 15 to be conveyed from the first conveyor roller 60 andthen pass through the position just under the recording portion 24, butalso for the trailing edge to pass through the auxiliary roller 47 ofthe path switching member 41.

When the image recording on the recording sheet 12 is completed at S160,the controller 130 at S170 determines, based on the image recordingcommand, whether an image-recorded face of the recording sheet 12 is afront face or not, that is, the controller 130 determines whether thereis a need to perform the image recording on a back face or not. When theimage recording needs to be performed on the back face (S170: Yes), thecontroller 130 controls the carriage drive motor 53 to move the carriage40, whereby the switcher 30 is moved or switched from the first powertransmission position to the second power transmission position.

Then at S180, the controller 130 rotates the conveyor motor 71 in thereverse direction. As a result, the conveyor rollers 60, 62, 45 arerotated in the direction in which the recording sheet 12 is conveyed inthe direction opposite to the first direction 15. It is noted that atS180 the first conveyor roller 60 is rotated in the clockwise direction,i.e., the second rotational direction, and the second conveyor rollers62 and the third conveyor rollers 45 are rotated in the counterclockwisedirection, i.e., the first rotational direction. Here, since therecording sheet 12 has passed through the auxiliary roller 47, the pathswitching member 41 has been pivoted to the flip orientation. Thus, therecording sheet 12 is conveyed in the direction opposite to the firstdirection 15 to the second conveyance path 67 while guided by the pathswitching member 41.

The controller 130 at S190 rotates the conveyor motor 71 in the reversedirection by a sixth rotational amount. Here, in the present embodiment,the sixth rotational amount is set at an amount enough for the recordingsheet 12 to pass through the second conveyance path 67 and reaches thefirst conveyor roller 60 at the leading edge of the recording sheet 12in the first direction 15.

The controller 130 then executes the processings at S140-S170 again. Asa result, an image is recorded on the back face of the recording sheet12. The processings at S120-S190 are one example of a second control.

When the image recording is completed for the front and back faces(S170: No), this flow goes to S200 at which the controller 130determines, based on the image recording command, whether there is anext page for image recording or not. When there is a next page (S200:Yes), the controller 130 moves the carriage 40, whereby the switcher 30is moved or switched from the second power transmission position to thefirst power transmission position.

The controller 130 then executes processings at S210 and S220. Here, theprocessings at S210 and S220 are respectively similar to the processingsat S80 and S90. It is noted that after the conveyor motor 71 is rotatedat S220 by the third rotational amount, the processing at S140 isexecuted again.

The controller 130 thereafter repeats the processings at S140-S220 untilthe controller 130 at S200 determines that there is no next page (S200:No).

When the controller 130 at S200 determines that there is no next page(S200: No), the controller 130 executes the processings at S100 andS110. As a result, the recording sheet 12 is discharged onto the outputtray 21.

<Effects of Embodiment>

In the present embodiment, the rotational driving power in the firstrotational direction is transmitted to the second conveyor rollers 62 bythe first power transmitter 26. On the other hand, the rotationaldriving power in the second rotational direction is transmitted to thesecond conveyor rollers 62 by the second power transmitter 27.Therefore, in the present embodiment, the second conveyor rollers 62 canbe rotatable only in one direction and can be rotatable in twodirections. That is, the second conveyor rollers 62 rotatable in onlyone direction in a certain situation can be made rotatable in twodirections in another situation.

Also, in the present embodiment, the first power transmitter 26 and thesecond power transmitter 27 are arranged such that the recording sheet12 passes through a position between the first power transmitter 26 andthe second power transmitter 27. As a result, the first powertransmitter 26 and the second power transmitter 27 are arranged atrespective areas where a speed of the recording portion 24 needs to beincreased, resulting in reduced size of the MFP 10.

Also, the MFP 10 including the one-way clutch and the first planetarygear mechanism 96 is preferable to realize functions of the first powertransmitter 26 and the second power transmitter 27.

Also, in the present embodiment, the first power transmitter 26transmits the rotational driving power in the first rotational directionfrom the first conveyor roller 60 to the second conveyor rollers 62 viathe second belt 83 but does not transmit the rotational driving power inthe second rotational direction to the second conveyor rollers 62 due tothe one-way clutch. In contrast, when the second power transmitter 27 isreceiving the rotational driving power in the second rotationaldirection, the planetary gear 98 is connected to and meshed with thesecond gear 101, and accordingly the second power transmitter 27transmits the rotational driving power in the second rotationaldirection to the second conveyor rollers 62. On the other hand, when thesecond power transmitter 27 is receiving the rotational driving power inthe first rotational direction, the planetary gear 98 is disconnectedfrom the second gear 101, and accordingly the second power transmitter27 does not transmit the rotational driving power in the firstrotational direction to the second conveyor rollers 62. In view of theabove, this construction is preferable to realize the above-describedeffects in which the second conveyor rollers 62 rotatable in only onedirection in a certain situation are made rotatable in two directions inanother situation.

Also, when the rotational driving power in the second rotationaldirection is being transmitted to the second conveyor rollers 62 by thesecond power transmitter 27, the rotational driving power in the secondrotational direction is transmitted by the first power transmitter 26 tothe second pulley 82 that is coaxial with the second conveyor rollers62. In this transmission, a mechanical error of components such as agear and a pulley may unfortunately cause a situation in which therotational speed of the second conveyor rollers 62 receiving the drivingpower transmitted by the second power transmitter 27 is faster than thatof the second pulley 82 receiving the driving power transmitted by thefirst power transmitter 26. In this situation, the second belt 83provided on the second pulley 82 may be slackened, causing the secondbelt 83 to be detached from the second pulley 82 or the first pulley 81.

To solve these problems, in the present embodiment, the rotational speedof the first conveyor roller 60 is reduced, and the rotational drivingpower is transmitted to the second conveyor rollers 62. Thisconfiguration makes it possible to reliably prevent the rotational speedof the second conveyor rollers 62 receiving the driving powertransmitted by the second power transmitter 27 from being faster thanthat of the second pulley 82 receiving the driving power transmitted bythe first power transmitter 26. Thus, it is possible to reliably preventthe second belt 83 from being detached as described above.

Also, in the present embodiment, when the third conveyor rollers 45 arerotated in the second rotational direction, the fourth conveyor rollers68 are rotated in the first rotational direction. Thus, in a case wherea leading edge of the recording sheet 12 in the second direction 16conveyed along the second conveyance path 67 is nipped between theroller pair of the driven roller 69 and the fourth conveyor rollers 68,and a trailing edge of the recording sheet 12 in the second direction 16is nipped between the roller pair of the spur 46 and the third conveyorrollers 45, both of the fourth conveyor rollers 68 and the thirdconveyor rollers 45 may pull the recording sheet 12. In order to solvethis problem, in the present embodiment, the fourth power transmitter 28speeds up the rotational driving power of the first conveyor roller 60in the first rotational direction and transmits the rotational drivingpower to the fourth conveyor rollers 68. As a result, when both of thefourth conveyor rollers 68 and the third conveyor rollers 45 pull therecording sheet 12, the fourth conveyor rollers 68 can pull out therecording sheet 12 nipped between the roller pair of the spur 46 and thethird conveyor rollers 45.

Also, in the present embodiment, when the rotational driving power inthe second rotational direction is transmitted from the first conveyorroller 60 to the supply rollers 25, the supply rollers 25 are rotated tosupply the recording sheet 12 toward the first conveyor roller 60. Inthis conveyance, the first conveyor roller 60 is rotated in the secondrotational direction, making it possible to correct the obliqueconveyance of the recording sheet 12 by the contact of the recordingsheet 12 with the first conveyor roller 60. This correction can berealized by a single motor, eliminating a need to provide a motorspecific to the supply rollers 25 to correct the oblique conveyance ofthe recording sheet 12.

Also, in the present embodiment, the switch lever 55 is moved by thecontact with the moving carriage 40, whereby a connecting state betweenthe first gear 78 and the second power transmitter 27 can be switched.That is, the movement of the carriage 40 is utilized to activate theswitcher 30, eliminating a need to provide a specific drive source foractivating the switcher 30.

Also, in the present embodiment, the first control allows the simpleximage recording on the recording sheet 12 to be appropriately performed.Also, the second control allows the duplex image recording on therecording sheet 12 to be appropriately performed. That is, only theconveyor motor 71 can reduce a length of time required for the simpleximage recording on a plurality of sheets, can correct the obliqueconveyance of the recording sheet 12 using the first conveyor roller 60,and can perform the duplex image recording.

<Modification>

In the present embodiment, when the conveyor motor 71 is rotated in theforward direction, the first conveyor roller 60 is rotated in the firstrotational direction, and the second conveyor rollers 62 and the thirdconveyor rollers 45 are rotated in the second rotational direction, butthe present invention is not limited to this configuration. Also, whenthe conveyor motor 71 is rotated in the reverse direction, the firstconveyor roller 60 is rotated in the second rotational direction, andthe second conveyor rollers 62 and the third conveyor rollers 45 arerotated in the first rotational direction, but the present invention isnot limited to this configuration. For example, in contrast to thepresent embodiment, the MFP 10 may be configured such that when theconveyor motor 71 is rotated in the forward direction, the firstconveyor roller 60 is rotated in the second rotational direction, andthe second conveyor rollers 62 and the third conveyor rollers 45 arerotated in the first rotational direction. Also, in contrast to thepresent embodiment, the MFP 10 may be configured such that when theconveyor motor 71 is rotated in the reverse direction, the firstconveyor roller 60 is rotated in the first rotational direction, and thesecond conveyor rollers 62 and the third conveyor rollers 45 are rotatedin the second rotational direction.

In the present embodiment, the first power transmitter 26 and the secondpower transmitter 27 are arranged such that the recording sheet 12passes through the area between the first power transmitter 26 and thesecond power transmitter 27, but the present invention is not limited tothis configuration. For example, both of the first power transmitter 26and the second power transmitter 27 may be arranged on one side of thearea in the right and left directions 9.

In the present embodiment, the one-way clutch is provided in the secondpulley 82 mounted on the shaft 64 of the second conveyor rollers 62, butthe present invention is not limited to this configuration. For example,the MFP 10 may be configured such that a one-way clutch is providedbetween the shaft 34 of the first conveyor roller 60 and the shaft 64 ofthe second conveyor rollers 62, a pulley for supporting the second belt83 is disposed so as to be meshed with the second pulley 82. Also, aone-way clutch is provided in the first pulley 81.

In the present embodiment, the planetary gear 98 is meshed with thesecond gear 101 mounted on the shaft 64 of the second conveyor rollers62, but the present invention is not limited to this configuration. Forexample, a gear may be disposed between the planetary gear 98 and thesecond gear 101. In this case, the gear and the second gear 101 are oneexample of a drive mechanism.

In the present embodiment, when the sun gear 97 is rotated in theclockwise direction, the planetary gear 98 is connected to the secondgear 101, but the present invention is not limited to thisconfiguration. For example, in contrast to the present embodiment, whenthe sun gear 97 is rotated in the counterclockwise direction, theplanetary gear 98 may be connected to the second gear 101. In this case,an odd number of the first intermediate gears 95 are provided while theeven number of the first intermediate gears 95 are provided in thepresent embodiment. In addition, an odd number of gears are providedbetween the planetary gear 98 and the second gear 101.

In the present embodiment, each of the first rotational amount, thethird rotational amount, and the fourth rotational amount of theconveyor motor 71 is set at an amount enough for the leading edge of therecording sheet 12 in the first direction 15 to be conveyed from thesupply tray 20 to the first conveyor roller 60, but the presentinvention is not limited to this configuration. For example, theconveyor motor 71 may be set at an amount by which the leading edge ofthe recording sheet 12 in the first direction 15 reaches the sensor 160.In this case, each of the second rotational amount and the fifthrotational amount is set at an amount enough for the trailing edge ofthe recording sheet 12 in the first direction 15 to be conveyed from thesensor 160 and pass through the position just under the recordingportion 24.

The present invention may be applied to an embodiment as illustrated inFIG. 11. This embodiment mainly omits the third conveyor rollers 45, thespur 46, and the third power transmitter 33 of the above-describedembodiment. In this embodiment, the second conveyance path 67 extendsfrom a position between the recording portion 24 and the second conveyorrollers 62 to an upstream side of the first conveyor roller 60 in thefirst direction 15. In this embodiment, the second conveyor rollers 62are one example of the second roller, and the second power transmitter27 is one example of the second power transmitter.

It is to be understood that the above-described modifications may beimplemented in combination as needed without departing from the scopeand spirit of the invention.

What is claimed is:
 1. An image recording apparatus, comprising: a drivesource configured to perform forward rotation and reverse rotation; afirst roller rotatable in a first direction by the forward rotation ofthe drive source to convey a conveyed medium in a conveying direction,the first roller being rotatable in a second direction by the reverserotation of the drive source, the second direction being reverse to thefirst direction; a recording device disposed downstream of the firstroller in the conveying direction and configured to record an image onthe conveyed medium; a second roller disposed downstream of therecording device in the conveying direction; a first power transmitterconfigured to transmit a first-direction driving power to the secondroller and not to transmit a second-direction driving power to thesecond roller, wherein the first-direction driving power is a rotationaldriving power of the first roller rotating in the first direction, andthe second-direction driving power is a rotational driving power of thefirst roller rotating in the second direction; and a second powertransmitter configured to transmit the second-direction driving power ofthe first roller to the second roller and not to transmit thefirst-direction driving power of the first roller to the second roller.2. The image recording apparatus according to claim 1, wherein thesecond roller is configured to rotate in one direction to convey theconveyed medium in the conveying direction when the first-directiondriving power is transmitted to the second roller by the first powertransmitter, and wherein the second roller is configured to rotate in adirection reverse to the one direction when the second-direction drivingpower is transmitted to the second roller by the second powertransmitter.
 3. The image recording apparatus according to claim 1,wherein the recording device is movable in main scanning directionsperpendicular to the conveying direction, and wherein each of the firstpower transmitter and the second power transmitter is disposed such thatthe conveyed medium passes through an area that is located between thefirst power transmitter and the second power transmitter in the mainscanning directions.
 4. The image recording apparatus according to claim1, wherein the first power transmitter comprises a one-way clutchmechanism configured to rotate the second roller when thefirst-direction driving power is transmitted to the one-way clutchmechanism, the one-way clutch mechanism being configured not to rotatethe second roller when the second-direction driving power is transmittedto the one-way clutch mechanism, and wherein the second powertransmitter comprises: a drive mechanism configured to drive the secondroller; and a planetary gear mechanism configured to be coupled to thedrive mechanism when the second-direction driving power is transmittedto the planetary gear mechanism, the planetary gear mechanism beingconfigured to be decoupled from the drive mechanism when thefirst-direction driving power is transmitted to the planetary gearmechanism.
 5. The image recording apparatus according to claim 4,wherein the first power transmitter comprises: a first pulley rotatabletogether with the first roller; a second pulley provided coaxially withthe second roller and comprising the one-way clutch mechanism; and abelt looped over the first pulley and the second pulley, wherein theplanetary-gear mechanism comprises: a rotatable sun gear; and aplanetary gear capable of being revolved in a direction of rotation ofthe sun gear in a state in which the planetary gear is meshed with thesun gear, wherein the second power transmitter comprises: a first rollergear provided coaxially with the first roller; a transmitter unitconfigured to transmit a rotational driving power of the first rollergear to the sun gear; and a second roller gear, as the drive mechanism,provided coaxially with the second roller, wherein, when thesecond-direction driving power is transmitted from the first roller gearto the sun gear of the planetary gear mechanism, the sun gear is rotatedin a direction in which the planetary gear is coupled to the secondroller gear, and wherein, when the first-direction driving power istransmitted from the first roller gear to the sun gear, the sun gear isrotated in a direction in which the planetary gear is decoupled from thesecond roller gear.
 6. The image recording apparatus according to claim4, wherein the second power transmitter comprises a speed reducerconfigured to reduce a rotational speed of the first roller and transmitthe second-direction driving power to the second roller.
 7. The imagerecording apparatus according to claim 1, further comprising: a thirdroller provided downstream of the second roller in the conveyingdirection; a third power transmitter configured to transmit a rotationaldriving power of the second roller to the third roller; and a switchmechanism disposed between the second roller and the third roller tocause an upstream edge of the conveyed medium in the conveying directionto be directed toward a reverse conveyance path which is continuous to amain conveyance path, wherein the main conveyance path is a pathextending from a position located upstream of the first roller in theconveying direction to a position located upstream of the second rollerin the conveying direction, and the conveyed medium is conveyed in theconveying direction through the main conveyance path.
 8. The imagerecording apparatus according to claim 7, wherein the third roller isconfigured to rotate in one direction to convey the conveyed medium inthe conveying direction when the first-direction driving power istransmitted to the second roller by the first power transmitter, andwherein the third roller is configured to rotate in a direction reverseto the one direction when the second-direction driving power istransmitted to the second roller by the second power transmitter.
 9. Theimage recording apparatus according to claim 7, further comprising: afourth roller disposed at the reverse conveyance path and configured toconvey the conveyed medium to the main conveyance path; and a fourthpower transmitter configured to transmit the first-direction drivingpower and the second-direction driving power to the fourth roller andconfigured to rotate the fourth roller in only one direction when any ofthe first-direction driving power and the second-direction driving poweris transmitted to the fourth roller.
 10. The image recording apparatusaccording to claim 9, wherein the fourth roller is configured to rotatein the one direction to convey the conveyed medium from the reverseconveyance path to the main conveyance path.
 11. The image recordingapparatus according to claim 9, wherein the fourth power transmittercomprises a speed increasing mechanism configured to make a rotationalspeed of the first roller in the first direction greater than arotational speed of the first roller in the second direction andtransmit the first-direction driving power to the fourth roller.
 12. Theimage recording apparatus according to claim 1, further comprising: atray configured to hold a medium as the conveyed medium; a supply rollerconfigured to supply the conveyed medium on the tray toward the firstroller; and a supply power transmitter configured to transmit thesecond-direction driving power to the supply roller and not to transmitthe first-direction driving power to the supply roller.
 13. The imagerecording apparatus according to claim 12, wherein the second roller isconfigured to rotate in one direction to convey the conveyed medium whenthe second-direction driving power is transmitted to the supply rollerby the supply power transmitter.
 14. The image recording apparatusaccording to claim 12, wherein the supply power transmitter comprises: asupply drive mechanism configured to drive the supply roller; and asupply planetary gear mechanism configured to be coupled to the supplydrive mechanism when the second-direction driving power is transmittedto the supply planetary gear mechanism, the supply planetary gearmechanism being configured to be decoupled from the supply drivemechanism when the first-direction driving power is transmitted to thesupply planetary gear mechanism.
 15. The image recording apparatusaccording to claim 14, wherein the supply planetary gear mechanismcomprises: a rotatable supply sun gear; and a supply planetary gearcapable of being revolved in a direction of rotation of the supply sungear in a state in which the supply planetary gear is meshed with thesupply sun gear; wherein the supply drive mechanism comprises: a firstroller gear provided coaxially with the first roller; a first supplypower transmitter configured to transmit a rotational driving power ofthe first roller gear to the supply sun gear; and a second supply powertransmitter configured to transmit a rotational driving power of thesupply planetary gear to the supply roller, wherein, when thesecond-direction driving power is transmitted to the supply sun gear ofthe supply planetary gear mechanism from the first roller gear, thesupply sun gear causes the supply planetary gear to be coupled to thesecond supply power transmitter, and wherein, when the first-directiondriving power is transmitted to the supply sun gear from the firstroller gear, the supply sun gear causes the supply planetary gear to bedecoupled from the second supply power transmitter.
 16. The imagerecording apparatus according to claim 15, wherein the second supplypower transmitter comprises an intermediate gear, wherein, when thesecond-direction driving power is transmitted to the supply planetarygear, the supply planetary gear is coupled to the intermediate gear, andwherein, when the first-direction driving power is transmitted to thesupply planetary gear, the supply planetary gear is moved away from theintermediate gear.
 17. The image recording apparatus according to claim1, wherein the recording device comprises a carriage movable in mainscanning directions perpendicular to the conveying direction, andwherein the image recording apparatus further comprises: a first rollergear configured to receive the rotational driving power of the firstroller; and a switcher comprising a contact member contactable with thecarriage moved in the main scanning directions, the switcher beingconfigured to be switched, by contact of the carriage with the contactmember, between a first position at which the switcher is coupled to thefirst roller gear and not coupled to the second power transmitter and asecond position at which the switcher is coupled to the first rollergear and coupled to the second power transmitter.
 18. The imagerecording apparatus according to claim 17, further comprising acontroller configured to control the drive source and the carriage,wherein the controller is configured to control the drive source toperform the forward rotation, in a state in which the switcher islocated at the first position, to convey the conveyed medium to aposition at which a downstream edge of the conveyed medium in theconveying direction passes through the first roller, and then controlthe drive source to perform the reverse rotation in a state in which theswitcher is located at the second position.
 19. The image recordingapparatus according to claim 12, wherein the recording device comprisesa carriage movable in main scanning directions perpendicular to theconveying direction, and wherein the image recording apparatuscomprises: a first roller gear configured to receive the rotationaldriving power of the first roller; and a switcher comprising a contactmember contactable with the carriage moved in the main scanningdirections, the switcher being configured to be switched, by contact ofthe carriage with the contact member, between a first position at whichthe switcher is coupled to the first roller gear and the supply powertransmitter and not coupled to the second power transmitter and a secondposition at which the switcher is coupled to the first roller gear andthe second power transmitter and not coupled to the supply powertransmitter.
 20. The image recording apparatus according to claim 19,further comprising a controller configured to control the drive sourceand the carriage, wherein the controller is configured, in a state inwhich the switcher is located at the first position, to: control thedrive source to perform the reverse rotation to convey the conveyedmedium from the tray to a position at which a downstream edge of theconveyed medium in the conveying direction reaches the first roller;then control the drive source to perform the forward rotation to conveythe conveyed medium to a position at which an upstream edge of theconveyed medium in the conveying direction passes through the firstroller; and then control the drive source to perform the reverserotation.
 21. An image recording apparatus, comprising: a drive sourceconfigured to perform forward rotation and reverse rotation; a firstroller rotatable in a first direction by the forward rotation of thedrive source to convey a sheet in a conveying direction, the firstroller being rotatable in a second direction by the reverse rotation ofthe drive source, the second direction being reverse to the firstdirection; a recording device provided downstream of the first roller inthe conveying direction to record an image on the sheet, the recordingdevice being reciprocable in main scanning directions perpendicular tothe conveying direction; a second roller provided downstream of therecording device in the conveying direction; a tray configured to holdthe sheet; a supply roller configured to supply the sheet on the traytoward the first roller; a first power transmitter configured totransmit a first-direction driving power to the second roller and not totransmit a second-direction driving power to the second roller, whereinthe first-direction driving power is a rotational driving power of thefirst roller rotating in the first direction, and the second-directiondriving power is a rotational driving power of the first roller rotatingin the second direction; a second power transmitter configured totransmit the second-direction driving power of the first roller to thesecond roller and not to transmit the first-direction driving power ofthe first roller to the second roller; a supply power transmitterconfigured to transmit the second-direction driving power to the supplyroller and not to transmit the first-direction driving power to thesupply roller; a first roller gear configured to receive the rotationaldriving power of the first roller; a switcher comprising a contactmember contactable with a carriage as the recording device moved in themain scanning directions, the switcher being configured to be switched,by contact of the carriage with the contact member, between a firstposition at which the switcher is coupled to the first roller gear andnot coupled to the second power transmitter and coupled to the supplypower transmitter and a second position at which the switcher is coupledto the first roller gear and coupled to the second power transmitter andnot coupled to the supply power transmitter; and a controller configuredto control the drive source and the carriage to execute; a first controlin which the controller controls the drive source to perform the reverserotation by a first rotational amount in a state in which the switcheris located at the first position, then controls the drive source toperform the forward rotation by a second rotational amount to convey thesheet to a position at which an upstream edge of the sheet in theconveying direction passes through the first roller, and then controlsthe drive source to perform the reverse rotation by a third rotationalamount; and a second control in which the controller controls the drivesource to perform the reverse rotation by a fourth rotational amount inthe state in which the switcher is located at the first position, thencontrols the drive source to perform the forward rotation by a fifthrotational amount to convey the sheet to the position at which theupstream edge of the sheet in the conveying direction passes through thefirst roller, and then controls the drive source to perform the reverserotation by a sixth rotational amount in a state in which the switcheris located at the second position.